Antiobesity effects and improvement of insulin sensitivity by 1-deoxynojirimycin in animal models

1-DNJ Alleviates Obesity-Induced Testicular Inflammation in Mice Model by Inhibiting IKKβ/ NF-kB Pathway

Obesity is associated with chronic inflammation that affects various organs in the body, including the reproductive system, which is a key factor in male infertility. 1-Deoxynojirimycin (1-DNJ) is a natural alkaloid in mulberry leaves, which has anti-inflammatory capabilities, yet, it's effects on obesity-induced inflammation-related male infertility remain unclear. Therefore, this research investigates the underlying mechanism by which 1-DNJ may mitigate fertility impairment in male mice caused by obesity-related inflammation. Male mice with high-fat diet (HFD)-induced obesity were treated with 1-DNJ or metformin for 8 weeks. Metabolic profiles were evaluated by enzyme method. Reproductive capacity was assessed by sperm viability, motility and counts, immunohistochemistry was performed to evaluate the testicular damage caused by obesity and inflammation. The inflammation was assessed by measuring the levels of tumor necrosis factor α (TNFα), interleukin 1β (IL-1β), and interleukin 6 (IL-6). The activation of IκB kinase β (IKKβ) and nuclear factor κB (NF-κB) was examined using western blot and immunohistochemistry. HFD induced obesity in mice with obvious lipid metabolism disorder. The obese male mice had a decreased testosterone level, impaired sperm motility, and increased inflammatory factors. 1-DNJ treatment improved the testosterone level in the obese mice, ameliorated the testicular structure damage and improve sperm viability. In addition, 1-DNJ treatment inhibited IKKβ/NF-kB signaling pathway and reduced inflammation in obese mice. 1-DNJ can improve the fertility of obese men by reducing obesity as well as obesity-induced inflammation. These findings provide new insights for 1-DNJ to alleviate inflammation caused by obesity and provide future possibilities for treating male infertility.

Mulberry leaf and its effects against obesity: A systematic review of phytochemistry, molecular mechanisms and applications

BACKGROUND

Obesity and hyperlipidemia can induce a variety of diseases, and have become major health problems worldwide. How to effectively prevent and control obesity has become one of the hot-spots of contemporary research. Mulberry leaf is the dried leaf of Morus alba L., which is approved by the Ministry of Health as a "homology of medicine and food", rich in diverse active constituents and with a variety of health effects including anti-obesity and anti-hyperlipidemia activities.

PURPOSE

The review attempts to summarize and provide the molecular basis, mechanism, safety and products for further exploration and application of mulberry leaf on the treatment on the control of weight gain and obesity.

METHODS

This review is conducted by using ScienceDirect, PubMed, CNKI and Web of Science databases following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

Based on the research progress of domestic and foreign scholars, the effective phytochemicals, molecular mechanisms and product applications of mulberry leaf in the prevention and treatment of obesity and related metabolic diseases were summarized.

CONCLUSION

Mulberry leaf has excellent medicinal and health care value in obesity treatment. However, its pharmacodynamic substance basis and molecular mechanisms need to be further studied.

1-Deoxynojirimycin containing Morus alba leaf-based food modulates the gut microbiome and expression of genes related to obesity

BACKGROUND

Obesity is a serious disease with an alarmingly high incidence that can lead to other complications in both humans and dogs. Similar to humans, obesity can cause metabolic diseases such as diabetes in dogs. Natural products may be the preferred intervention for metabolic diseases such as obesity. The compound 1-deoxynojirimycin, present in Morus leaves and other sources has antiobesity effects. The possible antiobesity effect of 1-deoxynojirimycin containing Morus alba leaf-based food was studied in healthy companion dogs (n = 46) visiting the veterinary clinic without a history of diseases. Body weight, body condition score (BCS), blood-related parameters, and other vital parameters of the dogs were studied. Whole-transcriptome of blood and gut microbiome analysis was also carried out to investigate the possible mechanisms of action and role of changes in the gut microbiome due to treatment.

RESULTS

After 90 days of treatment, a significant antiobesity effect of the treatment food was observed through the reduction of weight, BCS, and blood-related parameters. A whole-transcriptome study revealed differentially expressed target genes important in obesity and diabetes-related pathways such as MLXIPL, CREB3L1, EGR1, ACTA2, SERPINE1, NOTCH3, and CXCL8. Gut microbiome analysis also revealed a significant difference in alpha and beta-diversity parameters in the treatment group. Similarly, the microbiota known for their health-promoting effects such as Lactobacillus ruminis, and Weissella hellenica were abundant (increased) in the treatment group. The predicted functional pathways related to obesity were also differentially abundant between groups.

CONCLUSIONS

1-Deoxynojirimycin-containing treatment food have been shown to significantly improve obesity. The identified genes, pathways, and gut microbiome-related results may be pursued in further studies to develop 1-deoxynojirimycin-based products as candidates against obesity.

Glucose-lowering effect of Reducose® enriched with 1-deoxynojirimycin and l-leucine: Studies on insulin secretion in INS-1 cells and reduction of blood glucose in diabetic rats

The extract of mulberry leaf and its active ingredients have already been reported to have anti-diabetic effects; however, further studies are required to obtain better quality extracts and higher yields of active ingredients. Reducose® is a commercially available aqueous extract of mulberry leaves with a high content of active ingredients. In this study, the biological activities of Reducose®, 1-deoxynojirimycin, and l-leucine were evaluated using a glucose-stimulated insulin secretion (GSIS) assay. The GSIS assay results were expressed as the glucose-stimulated index (GSI). Considering the pharmacological safety in pancreatic β-cells, the appropriate non-toxic concentrations were selected by screening for cytotoxicity of Reducose®, 1-deoxynojirimycin, and l-leucine before the GSIS assay. The effect of Reducose®, 1-deoxynojirimycin, and l-leucine on glucose-stimulated insulin secretion in INS-1 cells was compared. Reducose®, 1-deoxynojirimycin, and l-leucine increased the GSI values more effectively than gliclazide (positive control). This was associated with an increase in protein expression, such as peroxisome proliferator-activated receptor-γ, insulin receptor substrate-2, activated pancreatic and duodenal homeobox-1, which are related to the regulation of pancreatic β-cell function and survival. In order to elucidate the effect of Reducose® in anti-diabetic effects, blood glucose levels, insulin levels, and liver and lipid concentrations were investigated in a Sprague-Dawley rat model of high-fat diet/streptozotocin-induced diabetes. We observed that administration of Reducose® can decrease fasting blood glucose levels and reduce the production of AST, ALT, TG, and TC to a similar extent as metformin (positive control). These results suggested that Reducose® play a role in promoting GSIS but not enough to show that the content and proportion of 1-deoxynojirimycin and l-leucine play an important role in the GSIS activity of Reducose®.

Metabolic engineering of Bacillus amyloliquefaciens for efficient production of α-glucosidase inhibitor1-deoxynojirimycin

Owing to the feature of strong α-glucosidase inhibitory activity, 1-deoxynojirimycin (1-DNJ) has broad application prospects in areas of functional food, biomedicine, etc., and this research wants to construct an efficient strain for 1-DNJ production, basing on Bacillus amyloliquefaciens HZ-12. Firstly, using the temperature-sensitive shuttle plasmid T2 (2)-Ori, gene ptsG in phosphotransferase system (PTS) was weakened by homologous recombination, and non-PTS pathway was strengthened by deleting its repressor gene iolR, and 1-DNJ yield of resultant strain HZ-S2 was increased by 4.27-fold, reached 110.72 mg/L. Then, to increase precursor fructose-6-phosphate (F-6-P) supply, phosphofructokinase was weaken, fructose phosphatase GlpX and 6-phosphate glucose isomerase Pgi were strengthened by promoter replacement, moreover, regulator gene nanR was deleted, 1-DNJ yield was further increased to 267.37 mg/L by 2.41-fold. Subsequently, promoter of 1-DNJ synthetase cluster was optimized, as well as 5'-UTRs of downstream genes in synthetase cluster, and 1-DNJ produced by the final strain reached 478.62 mg/L. Last but not the least, 1-DNJ yield of 1632.50 mg/L was attained in 3 L fermenter, which was the highest yield of 1-DNJ reported to date. Taken together, our results demonstrated that metabolic engineering was an effective strategy for 1-DNJ synthesis, this research laid a foundation for industrialization of functional food and drugs based on 1-DNJ.

Evaluation of mulberry leaves’ hypoglycemic properties and hypoglycemic mechanisms

The effectiveness of herbal medicine in treating diabetes has grown in recent years, but the precise mechanism by which it does so is still unclear to both medical professionals and diabetics. In traditional Chinese medicine, mulberry leaf is used to treat inflammation, colds, and antiviral illnesses. Mulberry leaves are one of the herbs with many medicinal applications, and as mulberry leaf study grows, there is mounting evidence that these leaves also have potent anti-diabetic properties. The direct role of mulberry leaf as a natural remedy in the treatment of diabetes has been proven in several studies and clinical trials. However, because mulberry leaf is a more potent remedy for diabetes, a deeper understanding of how it works is required. The bioactive compounds flavonoids, alkaloids, polysaccharides, polyphenols, volatile oils, sterols, amino acids, and a variety of inorganic trace elements and vitamins, among others, have been found to be abundant in mulberry leaves. Among these compounds, flavonoids, alkaloids, polysaccharides, and polyphenols have a stronger link to diabetes. Of course, trace minerals and vitamins also contribute to blood sugar regulation. Inhibiting alpha glucosidase activity in the intestine, regulating lipid metabolism in the body, protecting pancreatic -cells, lowering insulin resistance, accelerating glucose uptake by target tissues, and improving oxidative stress levels in the body are some of the main therapeutic properties mentioned above. These mechanisms can effectively regulate blood glucose levels. The therapeutic effects of the bioactive compounds found in mulberry leaves on diabetes mellitus and their associated molecular mechanisms are the main topics of this paper’s overview of the state of the art in mulberry leaf research for the treatment of diabetes mellitus.

Mulberry Leaf Supplements Effecting Anti-Inflammatory Genes and Improving Obesity in Elderly Overweight Dogs

Overweight and obesity, associated with various health complications, refer to abnormal or excessive fat accumulation conditions that harm health. Like humans, obesity is a growing problem in dogs, which may increase the risk of serious diseases such as diabetes and cancer. Mulberry leaf has shown potential anti-obesity and anti-diabetes effects in several studies. Our research studied the impact of mulberry leaf supplements in healthy old overweight dogs for 12 weeks. Blood and fecal samples were collected from the dogs before and after treatment for different analyses, including whole transcriptome and gut microbiome analysis. The Body Condition Score (BCS) and blood glucose levels were significantly decreased in all mulberry treatment groups, which justifies the anti-obesity effect of mulberry leaf in dogs. Throughout the whole transcriptome study, the downregulation of PTX3 and upregulation of PDCD-1, TNFRSF1B, RUNX3, and TICAM1 genes in the high mulberry group were found, which have been associated with anti-inflammatory effects in the literature. It may be an essential gene expression mechanism responsible for the anti-inflammatory and, subsequently, anti-obesity effects associated with mulberry leaf treatment, as confirmed by real-time polymerase chain reaction analysis. In microbiome analysis, Papillibacter cinnamivorans, related to the Mediterranean diet, which may cause anti-inflammatory effects, were abundant in the same treatment group. Further studies may be required to establish the gene expression mechanism and role of abundant bacteria in the anti-obesity effect of mulberry supplements in dogs. Overall, we propose mulberry leaves as a portion of food supplements for improving blood glucose levels and the anti-inflammation of blood in companion dogs.

The exploration and utilization of functional substances in edible insects: a review

Edible insects as food have been considered as a core future protein source. Not only are edible insects abundant in nutrient value, but also have numbers of functional substances, which could provide a multiple valuable benefits for humans. This review examines and summarizes the functional substances in edible insects and their special effects for people, as well as the use and prospects for these functional substances. There are many functional substances in edible insects, such as antimicrobial peptides, interferon, sex attractant hormones, cordycepin, active polysaccharides, microelement, chitin/chitosan, steroidal material, vitamin, lecithin, etc., which could provide multiple benefits for human beings. These special functional substances could help people enhance immunity, inhibit tumor, regulate intestinal function, relieve fatigue, anti oxidation, protect against colds, improve sleeping, promote the growth and development, as well as reducing blood sugar and blood pressure, among others. According to these valuable efficacies, the functional substances extracted from edible insects can be exploited mainly in three ways: edible insects are used to discover new medicines or health care products for people; and edible insects are applied in chemical, agricultural, food technology, pollutant treatment and textile sectors; as well as being consumed as animal feedstuff for livestock and other animals, which indirectly meet the different requirements for humans. Currently, edible insects have generated global interest to be developed as different forms of products and has promoted more research and development. However, pupae and larvae are still the main consumption ways in the market, which is unacceptable to most people. It is expected that the edible insect industry would be prosperous and sustainable by integrating the power of beneficial policies and regulations, huge consumer demand and proper strategies of promotion and production.

Graphical Abstract

A comprehensive review on the production, pharmacokinetics and health benefits of mulberry leaf iminosugars: Main focus on 1-deoxynojirimycin, d-fagomine, and 2-O-ɑ-d-galactopyranosyl-DNJ

Mulberry leaves are rich in biologically active compounds, including phenolics, polysaccharides, and alkaloids. Mulberry leaf iminosugars (MLIs; a type of polyhydroxylated alkaloids), in particular, have been gaining increasing attention due to their health-promoting effects, including anti-diabetic, anti-obesity, anti-hyperglycemic, anti-hypercholesterolemic, anti-inflammatory, and gut microbiota-modulatory activities. Knowledge regarding the in vivo bioavailability and bioactivity of MLIs are crucial to understand their role and function and human health. Therefore, this review is aimed to comprehensively summarize the existing studies on the oral pharmacokinetics and the physiological significance of selected MLIs (i.e.,1-deoxynojirimycin, d-fagomine, and 2-O-ɑ-d-galactopyranosyl-DNJ). Evidence have suggested that MLIs possess relatively good uptake and safety profiles, which support their prospective use for oral intake; the therapeutic potential of these compounds against metabolic and chronic disorders and the underlying mechanisms behind these effects have also been studied in in vitro and in vivo models. Also discussed are the biosynthetic pathways of MLIs in plants, as well as the agronomic and processing factors that affect their concentration in mulberry leaves-derived products.

Lycopene ameliorates insulin resistance and increases muscle capillary density in aging via activation of SIRT1

Lycopene (Ly) is a kind of hydrocarbon, which belongs to the family of tetraterpene carotene and exists in red fruits and vegetables. The decrease of capillary density and blood flow with age is a significant reason for the increase of mortality and morbidity. Herein, our study aims to explore the effects of Ly (a bioactive food compound) on vascular aging in vitro and in vivo and its potential mechanisms. The cytological results showed that Ly could promote the proliferation of human umbilical vein endothelial cell (HUVECs) and enhance the ability of HUVECs to form capillary-like structures. Furthermore, the expression of SIRT1 in aged HUVECs was up-regulated. In vivo, aging rats showed signs of insulin resistance and blood vessel damage. Additionally, the capillary density and blood flow were reduced during the vascular aging process in both D-gal-induced and naturally aging muscle. However, when Ly was given, these conditions could be reversed. Simultaneously, the contents of ATP, lactic acid and pyruvic acid were determined, and it was found that Ly could promote angiogenesis by increasing the utilization rate of glucose and promoting energy metabolism. Finally, in the insulin resistance cell model, we knocked down the SIRT1 and administrated with Ly, and found that it couldn't restore insulin transdution. In conclusion, all the data in this study demonstrate that Ly could reactivate SIRT1 and improve insulin resistance, which was a reversible cause of vascular aging.

Anti-Obesity Effects of Morus alba L. and Aronia melanocarpa in a High-Fat Diet-Induced Obese C57BL/6J Mouse Model

The present study investigated the synergic effect of extracts of Morus alba (MA) and Aronia melanocarpa (Michx.) (AR) against high-fat diet induced obesity. Four-week-old male C57BL/6J mice were randomly divided into five groups that were fed for 14 weeks with a normal diet (ND), high-fat diet (HD), HD with M. alba 400 mg/kg body weight (MA), HD with A. melanocarpa 400 mg/kg body weight (AR), or HD with a mixture (1:1, v/v) of M. alba and A. melanocarpa (400 mg/kg) (MA + AR). Treatment with MA, AR, and MA + AR for 14 weeks reduced high fat diet-induced weight gain and improved serum lipid levels, and histological analysis revealed that MA and AR treatment markedly decreased lipid accumulation in the liver and adipocyte size in epididymal fat. Furthermore, micro-CT images showed MA + AR significantly reduced abdominal fat volume. Expression levels of genes involved in lipid anabolism, such as SREBP-1c, PPAR-γ, CEBPα, FAS, and CD36 were decreased by MA + AR treatment whereas PPAR-α, ACOX1, and CPT-1a levels were increased by MA + AR treatment. Protein expression of p-AMPK and p-ACC were increased in the MA + AR group, indicating that MA + AR ameliorated obesity by upregulating AMPK signaling. Together, our findings indicate that MA and AR exert a synergistic effect against diet-induced obesity and are promising agents for managing obesity.

1-Deoxynojirimycin and its Derivatives: A Mini Review of the Literature

1-Deoxynojirimycin (1-DNJ) is a naturally occurring sugar analogue with unique bioactivities. It is found in mulberry leaves and silkworms, as well as in the metabolites of certain microorganisms, including Streptomyces and Bacillus. 1-DNJ is a potent α-glucosidase inhibitor and it possesses anti-hyperglycemic, anti-obese, anti-viral and anti-tumor properties. Some derivatives of 1-DNJ, like miglitol, miglustat and migalastat, were applied clinically to treat diseases such as diabetes and lysosomal storage disorders. The present review focused on the extraction, determination, pharmacokinetics and bioactivity of 1-DNJ, as well as the clinical application of 1-DNJ derivatives.

Does calorie restriction improve cognition?

Calorie restriction (CR) has been considered the most effective non-pharmacological intervention to counteract aging-related diseases and improve longevity. This intervention has shown beneficial effects in the prevention and treatment of several chronic diseases and functional declines related to aging, such as Parkinson's, Alzheimer's, and neuroendocrine disorders. However, the effects of CR on cognition show controversial results since its effects vary according to intensity, duration, and the period of CR. This review focuses on the main studies published in the last ten years regarding the consequences of CR on cognition in different neurological diseases and conditions of experimental animals. Also, possible CR mimetics are discussed. These findings highlight the potential beneficial effects of CR of up to 40 % on cognition when started early in life in non human animals.

Supplementation ofBacillus amyloliquefaciensAS385 culture broth powder containing 1-deoxynojirimycin in a high-fat diet altered the gene expressions related to lipid metabolism and insulin signaling in mice epididymal white adipose tissue

Supplementation ofBacillus amyloliquefaciensAS385 culture broth powder in high-fat diet restored adiposity, glucose tolerance and insulin sensitivity in mice.

Differential effects of red yeast rice, Berberis aristata and Morus alba extracts on PCSK9 and LDL uptake

BACKGROUND AND AIMS

The novel nutraceutical combination containing red yeast rice (monacolin K 3.3 mg), Berberis aristata cortex extract (Berberine 531.25 mg) and Morus alba leaves extract (1-deoxynojirimycin 4 mg) is effective in the management of elevated plasma low-density lipoprotein cholesterol (LDL-C) levels. The aim of the present study was to investigate the effects of the three components on proprotein convertase subtilisin/kexin type 9 (PCSK9), a key regulator of LDL receptor (LDLR) expression, in hepatocyte cell lines and to compare their effects on LDL cellular uptake.

METHODS AND RESULTS

HepG2 and Huh7 cells were incubated with B. aristata cortex extract (BCE), red yeast rice (RYR) and M. alba leaves extract (MLE) alone or in combination for 24 h. RYR (50 μg/mL) increased PCSK9 protein expression (Western blot analysis and ELISA), PCSK9 mRNA (qPCR) and its promoter activity (luciferase reporter assay). BCE (40 μg/mL) reduced instead PCSK9 expression, mRNA levels and promoter activity. MLE determined a concentration-dependent reduction of PCSK9 at the mRNA and protein levels, with a maximal reduction at 1 mg/mL, without significant changes of PCSK9 promoter activity. MLE also downregulated the expression of 3-hydroxy-3-methyl-3-glutaryl coenzyme A reductase and fatty acid synthase mRNA levels. The combination of RYR, BCE and MLE reduced the PCSK9 mRNA and protein levels, as well as the promoter activity. Finally, the single components and their combination induced LDL receptor and LDL uptake by the hepatocytes.

CONCLUSION

The positive effect of MLE on PCSK9 supports the rationale of using the nutraceutical combination of RYR, BCE and MLE to control hyperlipidemic conditions.

Cyanidin-3-O-galactoside-enriched Aronia melanocarpa extract attenuates weight gain and adipogenic pathways in high-fat diet-induced obese C57BL/6 mice

Aronia melanocarpa are a rich source of anthocyanins that have received considerable interest for their relations to human health. In this study, the anti-adipogenic effect of cyanidin-3-O-galactoside-enriched Aronia melanocarpa extract (AM-Ex) and its underlying mechanisms were investigated in an in vivo system. Five-week-old male C57BL/6N mice were randomly divided into five groups for 8-week feeding with a control diet (CD), a high-fat diet (HFD), or a HFD with 50 (AM-Ex 50), 100 (AM-Ex 100), or 200 AM-Ex (AM-Ex 200) mg/kg body weight/day. HFD-fed mice showed a significant increase in body weight compared to the CD group, and AM-Ex dose-dependently inhibited this weight gain. AM-Ex significantly reduced the food intake and the weight of white fat tissue, including epididymal fat, retroperitoneal fat, mesenteric fat, and inguinal fat. Treatment with AM-Ex (50 to 200 mg/kg) reduced serum levels of leptin, insulin, triglyceride, total cholesterol, and low density lipoprotein (LDL)-cholesterol. Real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that AM-Ex suppressed adipogenesis by decreasing CCAAT/enhancer binding protein α, peroxisome proliferator-activated receptor γ, sterol regulatory element-binding protein-1c, peroxisome proliferator-activated receptor gamma coactivator-1α, acetyl-CoA carboxylase 1, ATP-citrate lyase, fatty acid synthase, and adipocyte protein 2 messenger RNA (mRNA) expressions. These results suggest that AM-Ex is potentially beneficial for the suppression of HFD-induced obesity by modulating multiple pathways associated with adipogenesis and food intake.

Placental imprinted gene expression mediates the effects of maternal psychosocial stress during pregnancy on fetal growth

Imprinted genes uniquely drive and support fetoplacental growth by controlling the allocation of maternal resources to the fetus and affecting the newborn's growth. We previously showed that alterations of the placental imprinted gene expression are associated with suboptimal perinatal growth and respond to environmental stimuli including socio-economic determinants. At the same time, maternal psychosocial stress during pregnancy (MPSP) has been shown to affect fetal growth. Here, we set out to test the hypothesis that placental imprinted gene expression mediates the effects of MPSP on fetal growth in a well-characterized birth cohort, the Stress in Pregnancy (SIP) Study. We observed that mothers experiencing high MPSP deliver infants with lower birthweight (P=0.047). Among the 109 imprinted genes tested, we detected panels of placental imprinted gene expression of 23 imprinted genes associated with MPSP and 26 with birthweight. Among these genes, five imprinted genes (CPXM2, glucosidase alpha acid (GAA), GPR1, SH3 and multiple ankyrin repeat domains 2 (SHANK2) and THSD7A) were common to the two panels. In multivariate analyses, controlling for maternal age and education and gestational age at birth and infant gender, two genes, GAA and SHANK2, each showed a 22% mediation of MPSP on fetal growth. These data provide new insights into the role that imprinted genes play in translating the maternal stress message into a fetoplacental growth pattern.

A Systematic Review of the Medicinal Potential of Mulberry in Treating Diabetes Mellitus

Diabetes mellitus (DM) is a serious metabolic disorder which has reached epidemic proportions all over the world. Despite tremendous developments in medicinal chemistry, traditional medicine is still commonly used for the prevention and treatment of DM. Traditional herbal medicines have played a major role in the management of DM in Asian countries. In particular, mulberry has commonly been utilized in China for the treatment of DM for thousands of years. In the last decade, numerous preclinical findings have suggested that mulberry is a promising therapeutic agent for the treatment of DM, and the polyhydroxylated alkaloids, flavonoids and polysaccharides from mulberry may be the potential active components. The present review systematically summarizes the chemical composition of mulberry and the pharmacological effects of different medicinal parts on DM; these effects include influences on glucose absorption, insulin (INS) production/secretion, anti-oxidation and anti-inflammation processes. After summarizing our research findings, we will discuss the challenges and opportunities and explore the direction of future research and the potential for developing mulberry into pharmaceuticals for the widespread treatment of DM.

Mulberry leaf extract reduces the glycemic indexes of four common dietary carbohydrates

BACKGROUND

1-Deoxynojirimycin (DNJ), a component of mulberry leaf extract (MLE), reduces postprandial hyperglycemia by inhibiting intestinal a-glycosidase. The aim of this exploratory study was to investigate the effects of MLE on the glycemic indexes (GI) of common dietary carbohydrates.

METHODS

This single-center, randomized, open-label, 7-cycle self-controlled crossover study enrolled 15 healthy volunteers at the National Drug Clinical Trial Institution, Second Affiliated Hospital of Tianjin University of Traditional Chinese Medicine (June 2014 to December 2014). The participants were randomized to receive glucose (3 occasions), glucose+MLE, sucrose+MLE, maltose+MLE, and maltodextrin+MLE orally during 7 visits (every 3 days). Blood glucose level was tested at 15 minutes before and at 15, 30, 45, 60, 90, and 120 minutes after carbohydrate intake. The GI of each carbohydrate relative to glucose (GI = 100) was calculated using the incremental area under the curve method. Safety was assessed at each visit.

RESULTS

All participants completed the protocol. After carbohydrate ingestion, blood glucose level peaked at 30 minutes (glucose, glucose+MLE, sucrose+MLE, and maltose+MLE) or 45 minutes (maltodextrin+MLE) before returning to preprandial levels at 120 minutes. At 30 minutes, the change in blood glucose level was lower for sucrose+MLE, maltose+MLE, and maltodextrin+MLE than for glucose or glucose+MLE (P < .05). GI was lowest for sucrose+MLE (43.22 ± 17.47) and maltose+MLE (49.23 ± 22.39), intermediate for maltodextrin+MLE (75.90 ± 26.01), and higher for glucose+MLE (91.88 ± 27.24). MLE reduced the GIs for maltose, sucrose, maltodextrin, and glucose by 53.11%, 33.51%, 31.00%, and 8.12%, respectively. MLE was well tolerated.

CONCLUSIONS

Coconsumption of MLE with sucrose, maltose, or maltodextrin can reduce the GI values of these carbohydrates.

TRIAL REGISTRATION

Chinese Clinical Trial Registry Platform, no. ChiCTR-IPR-15006484. Registered on May 28, 2015.

Cloning, expression, and functional analysis of lysine decarboxylase in mulberry (Morus alba L.)

1-Deoxynojirimycin (DNJ) is the main bioactive compound of Morus alba L.. DNJ has pharmacological effects, including blood sugar level regulation and antiviral activity. In this study, the mulberry lysine decarboxylase gene (MaLDC), which is involved in the biosynthesis of DNJ alkaloids, was cloned, expressed, and functionally verified. MaLDC was induced and expressed in Escherichia coli BL21 (DE3). The recombinant soluble MaLDC protein had a relative molecular mass of 24.0 kDa. The protein was purified by Ni-NTA separation. The results showed that MaLDC protein could catalyze lysine decarboxylation to produce cadaverine. The K_m and V_max values were 19.2 μM and 3.31 μM/min, respectively. Quantitative real-time reverse transcription polymerase chain reaction revealed that MaLDC expression was positively correlated with DNJ content (P < 0.001), indicating that the MaLDC could encode a functional protein involved in the biosynthesis of DNJ alkaloid in mulberry. Our results provided a foundation for further studies of the enzymatic properties of LDC and established a basis for the analysis of key enzymes involved in the biosynthetic pathway of mulberry DNJ alkaloid.

Improved production of 1-deoxynojirymicin in Escherichia coli through metabolic engineering

Azasugars, such as 1-deoxynojirymicin (1-DNJ), are associated with diverse pharmaceutical applications, such as antidiabetic, anti-obesity, anti-HIV, and antitumor properties. Different azasugars have been isolated from diverse microbial and plant sources though complicated purification steps, or generated by costly chemical synthesis processes. But the biosynthesis of such potent molecules using Escherichia coli as a heterologous host provides a broader opportunity to access these molecules, particularly by utilizing synthetic biological, metabolic engineering, and process optimization approaches. This work used an integrated approach of synthetic biology, enzyme engineering, and pathway optimization for rational metabolic engineering, leading to the improved production of 1-DNJ. The production of 1-DNJ in recombinant E. coli culture broth was confirmed by enzymatic assays and mass spectrometric analysis. Specifically, the pathway engineering for its key precursor, fructose-6-phosphate, along with optimized media condition, results in the highest production levels. When combined, 1-DNJ production was extended to ~ 273 mg/L, which is the highest titer of production of 1-DNJ reported using E. coli.

Comparative transcriptome analysis reveals significant metabolic alterations in eri-silkworm (Samia cynthia ricini) haemolymph in response to 1-deoxynojirimycin

Samia cynthia ricini (Lepidoptera: Saturniidae) is an important commercial silk-producing insect; however, in contrast to the silkworm, mulberry leaves are toxic to this insect because the leaves contain the component 1-deoxynojirimycin (DNJ). A transcriptomic analysis of eri-silkworm haemolymph was conducted to examine the genes related to different metabolic pathways and to elucidate the molecular mechanism underlying eri-silkworm haemolymph responses to DNJ. Eight hundred sixty-five differentially expressed genes (DEGs) were identified, among which 577 DEGs were up-regulated and 288 DEGs were down-regulated in the 2% DNJ group compared to control (ddH₂O) after 12h. Based on the results of the functional analysis, these DEGs were associated with ribosomes, glycolysis, N-glycan biosynthesis, and oxidative phosphorylation. In particular, according to the KEGG analysis, 138 DEGs were involved in energy metabolism, glycometabolism and lipid metabolism, and the changes in the expression of nine DEGs were confirmed by reverse transcription quantitative PCR (RT-qPCR). Thus, DNJ induced significant metabolic alterations in eri-silkworm haemolymph. These results will lay the foundation for research into the toxic effects of DNJ on eri-silkworm as a model and provide a reference for the exploitation of new drugs in humans.

1-Deoxynojirimycin: Sources, Extraction, Analysis and Biological Functions

1-Deoxynojirimycin (DNJ), a natural polyhydroxylated piperidine alkaloid, is attracting growing attention due to its important biological functions. This paper introduces the discovery and origins of DNJ, its extraction, purification, and physiological functions in the treatment of diabetes. The mechanisms of DNJ in the inhibition of fat accumulation and tumor cell metastasis are also discussed. In addition, the prospects and challenges of DNJ for practical production are proposed. This work aims to provide technical advice on obtaining DNJ and a fuller understanding of its biological activities.

Central Administration of 1-Deoxynojirimycin Attenuates Hypothalamic Endoplasmic Reticulum Stress and Regulates Food Intake and Body Weight in Mice with High-Fat Diet-Induced Obesity

The α-glucosidase inhibitor, 1-deoxynojirimycin (DNJ), is widely used for its antiobesity and antidiabetic effects. Researchers have demonstrated that DNJ regulates body weight by increasing adiponectin levels, which affects energy intake and prevents diet-induced obesity. However, the mechanism by which centrally administered DNJ exerts anorexigenic effects has not been studied until now. We investigated the effect of DNJ in the hypothalamus of mice with high-fat diet-induced obesity. Results showed that intracerebroventricular (ICV) administration of DNJ reduced hypothalamic ER stress, which activated the leptin-induced Janus-activated kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT3) signaling pathway to cause appetite suppression. We conclude that DNJ may reduce obesity by moderating feeding behavior and ER stress in the hypothalamic portion of the central nervous system (CNS).

Metabolic Effect of 1-Deoxynojirimycin from Mulberry Leaves on db/db Diabetic Mice Using Liquid Chromatography-Mass Spectrometry Based Metabolomics

Metabolomics was applied to the liquid chromatography-mass spectrometry urinary metabolic profile of type 2 diabetes (T2DM) mice treated with mulberry 1-deoxynojirimycin (DNJ). The serum biochemical indicators related to T2DM like blood glucose, insulin, triglyceride, total cholesterol, nitrogen, malondialdehyde, and creatinine decreased significantly in the treated group. The histopathological changes in liver cells were marked by deformations and disruptions in central area of nuclei in DM mice, whereas DNJ treatment recovered regular liver cells with normal nuclei. Most of the metabolites of T2DM were significantly different from healthy controls in the bulk data generated. The level of 16 metabolites showed that the diabetic group was closer to the healthy group as the DNJ treatment time prolonged. Moreover, DNJ inhibited the activity of glucosidase on glucose, lipid, and amino acid metabolism. Our results showed the mechanism of DNJ treatment of T2DM and could fetch deep insights into the potent metabolite markers of the applied antidiabetic interventions.

Fate of d-Fagomine after Oral Administration to Rats

d-Fagomine is an iminosugar found in buckwheat that is capable of inhibiting the adhesion of potentially pathogenic bacteria to epithelial mucosa and reducing the postprandial blood glucose concentration. This paper evaluates the excretion and metabolism of orally administered d-fagomine in rats and compares outcomes with the fate of 1-deoxynojirimycin. d-Fagomine and 1-deoxynojirimycin show similar absorption and excretion kinetics. d-Fagomine is partly absorbed (41-84%, dose of 2 mg/kg of body weight) and excreted in urine within 8 h, while the non-absorbed fraction is cleared in feces within 24 h. d-Fagomine is partially methylated (about 10% in urine and 3% in feces). The concentration of d-fagomine in urine from 1 to 6 h after administration is higher than 10 mg/L, the concentration that inhibits adhesion of Escherichia coli. Orally administered d-fagomine is partially absorbed and then rapidly excreted in urine, where it reaches a concentration that may be protective against urinary tract infections.

Metabolic changes in the midgut of Eri silkworm after Oral administration of 1-deoxynojirimycin: A 1H-NMR-based metabonomic study

1-deoxynojirimycin (DNJ) is a natural D-glucose analogue and has a strong physiological activity in inhibiting α-glucosidase in vivo. The antidiabetic effects of DNJ in mice or other mammals were extensively explored, but the physiological and toxic roles of DNJ in insects was seldom reported. In this study, the biological effects of DNJ were examined in midgut extracts of fourth-instar larvae of Eri silkworm (Samia cynthia ricini, Saturniidae). Based on nuclear magnetic resonance (NMR) metabonomics technology, we analyzed the alterations of glycometabolism, lipids, and energy metabolism pathways in the midgut of S. cynthia ricini caused by DNJ. Pattern recognition analysis (partial least square-discriminant analysis, PLS-DA) showed that four groups of latex, 0.25% DNJ, 0.5% DNJ and the mixture of 0.5% DNJ and latex (1:1) were distinctly different from the control group. Moreover, several metabolic pathways of DNJ-mediated modulation in the midgut were identified. Compared with the control group, alanine, succinate, glutamate, and fumarate concentrations decreased in three groups of 0.5% DNJ, latex, and the mixture, choline levels increased in two DNJ groups, and trehalose levels increased in all experimental groups. Therefore, these results suggest that DNJ modulated lipid metabolism by limiting the hydrolysis pathways of phospholipids metabolism. Additionally, DNJ has a potent negative effect on energy metabolism by inhibiting the hydrolysis of trehalose, glycolysis and the tricarboxylic acid (TCA) cycle. Overall, DNJ, as a single-ingredient, is an efficient substance for modulating lipid metabolism and inhibiting energy metabolism.

1-Deoxynojirimycin: Occurrence, Extraction, Chemistry, Oral Pharmacokinetics, Biological Activities and In Silico Target Fishing

1-Deoxynojirimycin (DNJ, C₆H13NO₄, 163.17 g/mol), an alkaloid azasugar or iminosugar, is a biologically active natural compound that exists in mulberry leaves and Commelina communis (dayflower) as well as from several bacterial strains such as Bacillus and Streptomyces species. Deoxynojirimycin possesses antihyperglycemic, anti-obesity, and antiviral features. Therefore, the aim of this detailed review article is to summarize the existing knowledge on occurrence, extraction, purification, determination, chemistry, and bioactivities of DNJ, so that researchers may use it to explore future perspectives of research on DNJ. Moreover, possible molecular targets of DNJ will also be investigated using suitable in silico approach.

Six-Step Syntheses of (-)-1-Deoxyaltronojirimycin and (+)-1-Deoxymannonojirimycin from N-Z-O-TBDPS-l-serinal

Highly stereoselective six-step syntheses of (-)-1-deoxyaltronojirimycin (altro-DNJ) and (+)-1-deoxymannojirimycin (manno-DNJ) from N-Cbz-O-TBDPS-l-serinal are described. Key transformations involve a two-step preparation of a functionalized dihydropyridin-3-one as a common intermediate followed by Luche reduction and dihydroxylation (for altro-DNJ). The same sequence employing an epoxidation/epoxide opening in place of dihydroxylation furnishes manno-DNJ.

Effect of Wheat Flour Noodles with Bombyx mori Powder on Glycemic Response in Healthy Subjects

Recent trial results suggest that the consumption of a low glycemic index (GI) diet is beneficial in the prevention of high blood glucose levels. Identifying active hypoglycemic substances in ordinary foods could be a significant benefit to the management of blood glucose. It has been hypothesized that noodles with Bombyx mori powder are a low GI food. We evaluated GI and changes in postprandial glucose levels following consumption of those noodles and compared them with those following consumption of plain wheat flour noodles (control) and glucose (reference) in healthy subjects. Thirteen males (age: 34.2±4.5 years, body mass index: 23.2±1.1 kg/m2) consumed 75 g carbohydrate portions of glucose and the 2 kinds of noodle after an overnight fast. Capillary blood was measured at time 0 (fasting), 15, 30, 45, 60, 90, 120, and 180 min from the start of each food intake. The GI values were calculated by taking the ratio of the incremental area under the blood glucose response curve (IAUC) for the noodles and glucose. There was a significant difference in postprandial glucose concentrations at 30 and 45 min between the control noodles and the noodles with Bombyx mori powder: the IAUC and GI for the noodles with Bombyx mori powder were significantly lower than those for glucose and plain wheat flour noodles. The wheat flour noodles with Bombyx mori powder could help prevent an increase in postprandial glucose response and possibly provide an alternative to other carbohydrate staple foods for glycemic management.

An Evaluation of 1-Deoxynojirimycin Oral Administration in Eri Silkworm through Fat Body Metabolomics Based on (1) H Nuclear Magnetic Resonance

1-Deoxynojirimycin (DNJ), the main hypoglycemic constituent in mulberry (Morus alba) latex, has been extensively researched. Although there is considerable interest in the biological effects of DNJ, the roles of 1-deoxynojirimycin (DNJ) in glycometabolism and energy metabolism in insects have received little attention. In this paper, (1)H nuclear magnetic resonance ((1)H NMR) based metabonomic was performed to study the effects of the oral supplementation of 0.25% DNJ, 0.5% DNJ, latex, and the mixture of 0.5% DNJ and latex (1 : 1) on the fat body glycometabolism and energy metabolism of the fourth-instar larvae of Eri silkworms, Samia cynthia ricini. Metabolic pattern recognition analysis (partial least square-discriminant analysis, PLS-DA) of fat body extracts indicated that the groups of 0.25% DNJ, 0.5% DNJ, latex, and the mixture of 0.5% DNJ and latex (1 : 1) were significantly different from the control group. Further, compared to the control group, the metabolites levels of lactate, trehalose, succinate, malate, and fumarate were remarkably changed in experimental groups, which were involved in glycolysis, hydrolysis of trehalose, and tricarboxylic acid (TCA) cycle. Our results indicate that DNJ has a positive impact on the reverse energy metabolism of Eri silkworms and metabonomic analysis based on NMR can be used as a tool to identify potential biomarkers.

1-Deoxynojirimycin Alleviates Insulin Resistance via Activation of Insulin Signaling PI3K/AKT Pathway in Skeletal Muscle of db/db Mice

1-Deoxynojirimycin (DNJ) is widely used for the treatment of diabetes mellitus as an inhibitor of intestinal α-glucosidase. However, there are few reports about its effect on insulin sensitivity improvement. The aim of the present study was to investigate whether DNJ decreased hyperglycemia by improving insulin sensitivity. An economical method was established to prepare large amounts of DNJ. Then, db/db mice were treated with DNJ intravenously (20, 40 and 80 mg·kg(-1)·day(-1)) for four weeks. Blood glucose and biochemical analyses were conducted to evaluate the therapeutic effects on hyperglycemia and the related molecular mechanisms in skeletal muscle were explored. DNJ significantly reduced body weight, blood glucose and serum insulin levels. DNJ treatment also improved glucose tolerance and insulin tolerance. Moreover, although expressions of total protein kinase B (AKT), phosphatidylinositol 3 kinase (PI3K), insulin receptor beta (IR-β), insulin receptor substrate-1 (IRS1) and glucose transporter 4 (GLUT4) in skeletal muscle were not affected, GLUT4 translocation and phosphorylation of Ser473-AKT, p85-PI3K, Tyr1361-IR-β and Tyr612-IRS1 were significantly increased by DNJ treatment. These results indicate that DNJ significantly improved insulin sensitivity via activating insulin signaling PI3K/AKT pathway in skeletal muscle of db/db mice.

Chronic adjunction of 1-deoxynojirimycin protects from age-related behavioral and biochemical changes in the SAMP8 mice

Several studies have indicated that a caloric restriction mimetic or treatment for type 2 diabetes may reverse brain aging. Therefore, we investigated the effect of 1-deoxynojirimycin (DNJ), an alkaloid acting as an inhibitor of α-glucosidase, on age-related behavioral and biochemical changes. SAMP8 mice were randomly assigned to a control group labeled "old" or to the 10- or 20-mg/kg/day DNJ groups. The mice in the DNJ groups were administered DNJ orally from 3 to 9 months of age, and then, a "young" control group was added to analyze the age effect. The old controls exhibited significant declines in sensorimotor ability, open-field anxiety, spatial and nonspatial memory abilities, and age-related biochemical changes, including decreased serum insulin level; increased levels of insulin-like growth factor 1 receptor, presynaptic protein synaptotagmin-1, and astrocyte activation; and decreased levels of insulin receptor, brain-derived neurotrophic factor, presynaptic protein syntaxin-1, and acetylation of histones H4 at lysine 8 in the dorsal hippocampus. Significant correlations exist between the age-related behavioral deficits and the serological and histochemical data. Chronic DNJ treatment alleviated these age-related changes, and the 20-mg/kg/day DNJ group showed more significant improvement. Thus, DNJ may have the potential to maintain successful brain aging.

Mulberry 1-Deoxynojirimycin Inhibits Adipogenesis by Repression of the ERK/PPARγ Signaling Pathway in Porcine Intramuscular Adipocytes

Intramuscular fat (IMF), which is modulated by adipogenensis of intramuscular adipocytes, plays a key role in pork quality associated with marbling, juiceness, and flavor. However, the regulatory mechanism of 1-deoxynojirimycin (DNJ) on adipogenesis is still unknown. Here, we found that both DNJ (2.0, 3.0, 4.0, 5.0, and 6.0 μM) and rosiglitazone (RSG; 0.1, 0.2, 0.3, 0.4, and 0.5 mM) had no effect on cell viability. Moreover, 4 μM DNJ significantly inhibited adipogenesis, whereas 0.4 mM RSG increased lipogenesis of porcine intramuscular adipocytes. Interestingly, DNJ sharply inhibited phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2), but did not change phosphorylation of AKT (protein kinase B) in intramuscular adipocytes. We further found that the inhibitory adipogenesis of DNJ was attenuated by RSG via up-regulation of PPARγ. On the basis of the above findings, we suggest that DNJ inhibited adipogenesis through the ERK/PPARγ signaling pathway in porcine intramuscular adipocytes.

A 1H-NMR Based Study on Hemolymph Metabolomics in Eri Silkworm after Oral Administration of 1-Deoxynojirimycin

We aimed to investigate whether 1-deoxynojirimycin (DNJ) modulates glycometabolism and has toxicity in Eri silkworm (Samia cynthia ricini, Saturniidae). In this paper, hemolymph metabolites were used to explore metabolic changes after oral administration of DNJ or mulberry latex and to characterize the biological function of DNJ at the metabolic and systemic levels. Hemolymph samples were collected from fourth-instar larvae of Eri silkworm and ex-vivo high-resolution 1H nuclear magnetic resonance (NMR) spectra were acquired from the collected hemolymph samples. Then the obtained spectra were analyzed by principal component analysis (PCA) and independent-samples t-test. Metabolic pattern recognition analysis of hemolymph samples indicated that the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) were significantly different from the control group. Moreover, compared to the control group, the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) showed the decreased levels of citrate, succinate, fumarate, malate, and glutamine in hemolymph, the groups of 0.25% DNJ and the mixture of 0.5% DNJ and latex (1:1) showed the increased levels of trehalose and lactate. In addition, mulberry leaves exude latex was highly toxic to Eri silkworm because rich unidentified high-molecular-weight factor (s) acted as toxic substances. In our results, latex caused 20 deaths among 50 fourth-instar larvae of Eri silkmoth, but DNJ or the mixture did not caused death. All these results suggest that DNJ has a positive impact on the reverse glycometabolism by modulating glycometabolism and inhibiting glucogenesis and energy metabolism. DNJ is a secure substance as a single-ingredient antidiabetic medicine due to its nontoxicity and bioactivity.

1-deoxynojirimycin isolated from Bacillus subtilis improves hepatic lipid metabolism and mitochondrial function in high-fat-fed mice

The aim of this study was to determine whether 1-deoxynojirimycin (DNJ) isolated from Bacillus subtilis MORI beneficially influences lipid metabolism and mitochondrial function in the liver of mice fed a high-fat diet in addition to the anti-obesity properties of DNJ. Male C57BL/6 mice (n = 29; 5 weeks old) were randomly assigned to three groups: normal control diet (CTL, n = 10), high-fat diet (HF, n = 10), and high-fat diet supplemented with DNJ (DNJ, n = 9). After 12 weeks, the HF group exhibited higher overall weight gain, of the liver, and of various fat pads than the CTL and DNJ groups did. The HF group also showed greater expression of C/EBPα and CD36 mRNA in the liver than that in the CTL and/or DNJ groups. In addition, mRNA expressions of AAC and FAS were lower, while mRNA expression of PGC-1β was higher in the liver of the DNJ group than that of the HF group. The hepatic expression of p-AMPK/AMPK was higher in the DNJ group than in the HF group. This study provides novel insight into the protective effect of DNJ supplementation against obesity-induced hepatic lipid abnormalities and mitochondrial dysfunction.

Text mining of the classical medical literature for medicines that show potential in diabetic nephropathy

Objectives. To apply modern text-mining methods to identify candidate herbs and formulae for the treatment of diabetic nephropathy. Methods. The method we developed includes three steps: (1) identification of candidate ancient terms; (2) systemic search and assessment of medical records written in classical Chinese; (3) preliminary evaluation of the effect and safety of candidates. Results. Ancient terms Xia Xiao, Shen Xiao, and Xiao Shen were determined as the most likely to correspond with diabetic nephropathy and used in text mining. A total of 80 Chinese formulae for treating conditions congruent with diabetic nephropathy recorded in medical books from Tang Dynasty to Qing Dynasty were collected. Sao si tang (also called Reeling Silk Decoction) was chosen to show the process of preliminary evaluation of the candidates. It had promising potential for development as new agent for the treatment of diabetic nephropathy. However, further investigations about the safety to patients with renal insufficiency are still needed. Conclusions. The methods developed in this study offer a targeted approach to identifying traditional herbs and/or formulae as candidates for further investigation in the search for new drugs for modern disease. However, more effort is still required to improve our techniques, especially with regard to compound formulae.

Pharmacokinetic mechanism of enhancement by Radix Pueraria flavonoids on the hyperglycemic effects of Cortex Mori extract in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus, characterized by abnormal blood glucose evaluation, is a serious chronic disease. In the treatment of the disease, α-glycosidase inhibitors play an important role for controlling the postprandial blood glucose level. Cortex Mori, a traditional Chinese herbal medicine, has a long history of use for the treatment of headaches, cough, edema and diabetes. Modern pharmacological studies have shown that the herb has beneficial effects on the suppression of postprandial blood glucose levels by inhibiting α-glycosidase activity in the small intestine. 1-Deoxynojirimycin (DNJ), the main active ingredient of this herb, is recognized as a potent α-glycosidase inhibitor. Our previous studies have shown that the hypoglycemic effect of Cortex Mori extract (CME) was significantly improved when giving CME in combination with Radix Pueraria flavonoids (RPF). In the present study, the pharmacokinetics and intestinal permeability of DNJ were comparatively investigated in rats after being given orally or by intestinal perfusion with CME alone or in CME-RPF pairs, to explore the mechanism of this synergistic effect.

MATERIALS AND METHODS

The role of RPF on the plasma and urine concentrations of DNJ from CME orally administered was investigated. Four groups of rats received a single oral dose of either CME or CME-RPF, at DNJ equivalent doses of 20 and 40mg/kg, respectively. After dosing, plasma and urine were collected and assayed by LC/MS/MS. In addition, another two groups of rats were used for small intestinal perfusion with CME or CME-RPF at DNJ concentration of 10µM.

RESULTS

Compared to the data when dosing with CME alone, the Cmax of DNJ were decreased from 5.78 to 2.94µg/ml (p<0.05) and 10.66 to 5.35µg/ml (p<0.01); Tmax were delayed from 0.40 to 0.55h and 0.35 to 0.50h (p<0.05); and MRT were significantly prolonged from 1.14 to 1.72h (p<0.05) and 0.95 to 1.62h (p<0.01), after dosing with CME-RPF at DNJ doses of 20 and 40mg/kg, respectively. In addition, the urinary recovery of DNJ over the first 4h after dosing significantly decreased from 48.76% to 33.86%. Effective permeability (Peff) of DNJ was decreased from 7.53×10(-3) to 3.09×10(-3)cm/s (p<0.05) when RPF was added to CME, when it was evaluated using the rat intestinal perfusion model.

CONCLUSIONS

All the above results demonstrate that RPF was able to suspend and delay the absorption of DNJ, but did not affect the total amount of DNJ in the body. The resulting higher concentration of DNJ in the small intestine produced a relatively stronger effect of depressing the elevation of the postprandial blood glucose level. These findings support the important role of RPF in the application of CME on blood glucose control.